Microstructural Evolution of Severely Plastically Deformed Austenitic Stainless Steel Using Precession Electron Diffraction
Yaakov S. Idell, Jorg Wiezorek
The properties of austenitic stainless steel can be vastly improved through thermo-mechanical processing using severe plastic deformation (SPD) techniques. Quantifying the microstructure- property relationships for the ultrafine- and nano-scale grain refined and often two-phase microstructures with conventional experimental tools is challenging. An orientation imaging microscopy (OIM) technique using automated acquisition and indexing of precession electron diffraction patterns in the transmission electron microscope (TEM) enables determination of structural metrics, such as grain size and morphology, phase fraction, texture, and grain boundary character, with local specificity from statistically significant and representative data sets with the required nanometer spatial resolution. We conducted a cross sectional study of the depth-dependent microstructure in austenitic stainless steel following SPD by linear plane-strain machining and its evolution during annealing at temperature up to 650°C. Complemented by X-ray diffraction, conventional TEM, hardness indentation and magnetometry, microstructure-property relationships have been determined. We acknowledge support from the Nuclear Regulatory Commission, NRC-38-009-935.